Attachment plug



7 m g 1 H W; e m. wwmm 1, QM E ,m 2 e a A BOGGILD ATTACHMENT PLUG Filed March 1, 1938 Oct. 31, 1939.

Patented Oct. 31, 1939 2,178, v

ATTACHMENT PLUG Axel Boggild, Trumbull, Conn assignor to General Electric Company, a corporation of New York Application March 1, 1938, Serial No. 193,315

4 Claims. (Cl. 173-343) The present invention relates to screw thread the parallel sides ll of the member to to preattachment plugs, and more particularly to atvent the shell from turning relative to the base, tachment plugs which are employed to connect in the manner indicated above. This opening is portable electrical devices with sources of ouralso made large enough to prevent the contact rent supply. member is where it rises above the member it) 533 The object of my invention is the provision of from making electrical contact with the screw an improved attachment plug which is simple in shell t. The small opening it is arranged to construction, reliable in operation and cheap to receive that portion or" the contact member 29 manufacture. which rises above the member til. It is made of In the accompanying drawing Fig. 1 is a side such size that the contact can pass freely through 10 elevation of an attachment plug, Fig. 2 is a crossit and when so passed can be properly positioned, sectional view through the plug; Fig. 3 is a crossand the inturned end part 2! will rest flat-wise sectional view of the base with the contact strucon the top of the screw shell and establish electure removed; Fig. 4 is an exploded view of the trical contact therewith and the lower part will plug elements, and Fig. 5 is an illustration of be disposed in one of the openings l3. 15*:

an assembling pin which has been removed from The contact member i8 is located chiefly in the plug base subsequent to assembly in order the other opening !3 in the base and has a relato illustrate the holding features. tively long inturned end or part 22 which makes Referring to the drawing, the base portion or electrical contact with a center contact to be rethe plug is shown at B and may be formed of any ferred .to later. The contact member extends 20 suitable moldable composition, for example, a through a narrow opening 23 disposed in an elephenolic condensation product and filler. The ment or disk 2 which is formed of insulating composition should be sufiiciently tough so that material such as fiber, or the like. The disk is it may not be easily broken and should have suiseated firmly on the top portion iii of the screw ficient strength to withstand the pressures to shell in such a position that the disk 24 and top 25 which it is subjected in the assembling operaportion it cooperate with the extended portion tion. On the lower end of the base is a knurled 2i of the contact 29 to, clamp the contact befi e l 'to facilitate sc w g the P ug into and tween the elements. In the contact part 22, the out of a receiving part such as a lamp socket, or disk2 i and the member iii are alined holes to 30 other receptacle. receive the center contact or assembling pin 25 30 Rising above e flange there s a Cylindrical when the latter is seated upon the base. The part which terminates in a shoulder 8 upon which pin 25 is provided with a shank 23 and a head 21 the lower edge Of a thi et Screw Shell 5 which forms the center contact of the plug and is seated. Ris n above Shoulder central which makes electrical Contact with the inturned member H] which has two flat parallel sides it part; 22 f the t t m; While t 31 has 35 Which prevent the Shell 9 from turning When been shown integral with the shank 26 it is obt p us s s w i a receptacle. On each vious that these may be formed in separate pieces. side of the member it a e relatively p In assembled position the pin is seated within a cesses l2 which are fo decrease the recess or opening 28 formed in the base structure amount of Composition Contained in the base, iL'in which position it securely holds the elements 40 thereby effecting a saving in material as well f the plug in position upon the base as in weight. Two parallel openings l3 are formed The plug thus far dfiscflbed is Shawn in in the member In and for simplicity f assembly sembled position in 2 and is similar to that of the plug the parts an made idenllcal' Each desoribedin Letters Patent No.1,830,597, granted opening is of rectangular cross-section and eX- to Ford 3 Ennis on November 3, In the 45 tends entir 61y through the plug base from top to patented construction the. shank of the pin is bottom i threaded or serrated and is driven into the open- The shell 9 has cyhndncal Demon M Whlch ing in the base structure so'that the threads or i rovided with the-usual screw threads i5 for eigagement with corresponding threads in the serrations engage the walls of the recess thereby cooperating receptacle. It is also provided it holding the pin frictionally in engagement with an integral top I6 having two openings one of the base and maintaining the contact structure which is much larger than the other. On oppoin asse b e relationship- While this construcsite sides of the larger opening are two downtion forms an excellent plug device, threading wardly extending ears I! which cooperate with or serrating the pin is an expensive operation 55 which may be eliminated by the construction of the present invention now to be described.

In lieu of serrating the pin, the opening or recess 28 is formed with a plurality of longitudinal ridges or ribs 29 projecting from the wall of the recess around the periphery thereof toward the axis of the opening. The shank of the pin 25 is left untouched, so that when it is driven into the base in assembling the plug the projecting ridges 29 will score or indent the circumference of the pin and imbed themselves therein, thereby forming a highly effective frictional engagement of the pin with the base. The pin is made of a metal of suitable hardness such that it may be scored by the ridges, for example, an aluminum alloy. As an illustration of the indentations formed by the ridges, a pin which has been removed from an assembled plug is shown by Fig. 5, and it will be seen that the ridges 29 have formed the grooves 30 in the pin. In addition to forming a cheaply manufactured and efiective holding means for the pin, the grooved construction prevents breakage of the composition base as the pin is driven into the base in the assembling operation. Notwithstanding the fact that the ridges are formed of composition and the contact pin of metal, the projections score the pin rather easily and thus stress is not placed upon the composition base, so that cracking or shattering of the base is prevented and the number of defective plugs occasioned in the manufacturing process is thereby reduced. It is important to eliminate all cracking of the base, however minute, because such cracks often lead to failure of the plug when put in use by screw threading into a receptacle.

It will be apparent that the base is molded wholly of insulating material and that no metal inserts of any character are required to support the contact structures. Furthermore, the ribs or ridges 2% are molded integrally with the base 6 without extra cost so that the cost of manufacture for a securing means between the contact pin and the base structure is materially reduced. Also, all of the electrical parts including the screw shell 9, the contact members l8 and 20, one of which is in contact with the shell and the other of which is in contact with the center contact or pin, are all fastened to the base by a single means constituting the pin 25. This pin may be driven in place by a single operation, that is, by a light hammer blow or press, in which position it is securely held by the frictional fit between the pin and ridged opening. The pin will not become loosened in use because threading the plug into a socket merely increases the pressure of the socket base upon the pin, tending to force it further into the base. The ridged construction aids such an effect inasmuch as the pin may slide slightly longitudinally of the ridges to seat itself further on the base without becoming loosened. As a result of the simplification of the parts and the use of the securing means constituting the ridges 29, the cost of ie device is materially reduced over prior constructions and the assembling operation may be made easily and quickly.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. In an attachment plug, a base of insulating material, a pair of contacts mounted on said base, means to insulate said contacts one from the other, said base having a pin receiving opening, the wall of said opening being provided with integral means projecting toward the center of said opening, and a pin adapted to secure said contacts and said insulating means to said base, said pin having a driving fit within said opening and said projecting means scoring said pin to secure it to said base.

2. In an attachment plug, a base of insulating material having a pin receiving opening formed with longitudinal ridges disposed peripherally around the wall of said opening, said base and said ridges being molded integrally as a unit, a pair of electrical contacts disposed in said base, insulating means separating said contacts one from the other and a pin making a driving fit in said opening and adapted to secure said contacts and insulating means to said base, said ridges being imbedded in said pin as said pin is driven into said opening.

3. In an attachment plug, a base of insulating material having a pin receiving opening, the wall forming said opening being provided with integral projecting means, a shell having a pair of openings therein mounted on said base, an insulating disk having a slot overlying said shell, a pair of contacts both having bent ends, said contacts being located in said base, one of said contacts extending through one of the openings in said shell and having its bent end disposed between said shell and said disk in contact with said shell, the other of said contacts extending through the other opening in said shell and through the slot in said insulating disk and having its bent end overlying said disk, and a pin having a driving fit within said opening, said pin making electrical connection with the bent end of said second-mentioned contact and uniting said parts on said base, said projecting means cooperating with said pin to secure the pin on said base.

4. In an attachment plug, the combination of an insulating base having a central fiat sided member containing a pin receiving opening, the wall forming said opening being provided with longitudinal projecting ridges, a screw shell mounted on said member, said shell having a pair of ears engaging the sides of the member to prevent relative turning thereof, and being provided with a pair of openings in the top surface of the shell, a pair of axially extending contacts located within the base, both of which have bent ends, the bent end of one of said contacts extending through one of the openings in said shell and making electrical contact with the top of the shell, an insulating disk covering one end of the base and provided with a slot therein, the bent end of the other of said contacts extending through the other opening and slot and a pin having a body portion which makes a driving fit with the ridged wall of said pin receiving opening and is in electrical communication with the bent end of the second of said contacts, and also forms the center contact of the plug and unites said parts.

AXEL BOGGILD. 

